leayitt



4 'Sheet -Sheet 1.

(No Model;)

I. M; LEAVITT,

STAMPING PRESS.

Patented Aug. 28, 1888.

Sheets-Sheet 2 (No Mode 1.)-

r. M. LEAVITT.

STAMPING PRESS.

Patented Aug.28, 1888.

WITNESSES. %/W v,

- 4 Shee'ts-Sheet 3. F. M. LEAVITT,

STAMPING PRESS.

(No Model.)

Ill IIIIT Patented Aug. 28, 1888.

u. PETERS. Pnmmhu rm. Washington. D, c.

4o jection which applies to cams is that, owing to NITE STATES FRANK M. LEAVITT, OF BROOKLYN, NEW YORK.

STAMPING-PRESS.

SPECIFICATION forming part of Letters Patent No. 388,698, dated August 28, 1888.

Application filed January 13, 1888.

To all whmn it may concern:

Be it known that I, FRANK M. LEAVITT, of Brooklyn, Kings county, New York, have invented certain new and useful Improvements in Stamping or Drawing Presses, of which the following is a specification.

My invention relates more especially to large and powerful presses for drawing sheet metal in large and deep forms, such as for large pans, kettles, and other vessels. In this class of presses the sheet-metal blank is placed over the mouth of the dieand there held by an annular clamp or blank-holder While the plungerdie descends within the annular holder and forces the sheet metal into the lower die, thus stamping or drawing it into the desired form. These actions therefore require that the blank holder should first descend forcibly against the margin of the blankand there pause, holding the blank firmly upon the die, while the plunger continues to descend within the holder and forces or draws the middle of the blank into the die, thus imparting the proper shape thereto. The holder still remains in its holding position during the upstroke of the plunger until the plunger is withdrawn, when the blank-holder rises with the plunger to release and permit the removal of the stamped article and leave the press ready to receive the next blank. Now, the stroke of the plunger is usually effected by a simple crank motion, while the motion of the blank-holder is usually effected by cams which are so formed as to give the desired pause in the action of the holder relatively to the action of the plunger. Cams can of course be readily formed to impart the proper motion and pause to the holder relatively to the motion of the plunger in a perfect manner; but a great obthe great strains exerted in machines of this class, the pressure and friction on the camsurfaces are so great as to cause rapid and destructive wear, which soon renders the action of the cams inaccurate, so as to require frequent adjustment, repairs, or renewals, which are bothtroublesome and expensive.

The object of my invention is therefore to effect the relative motions of plunger and blank-holder in an accurate and durable manner without the use of cams at all, and this I Serial No. 260.610. (No model.)

of the press, but with the plunger and holder at the top of the stroke. Figs. 4, 5, 6, and 7 are diagrammatic views showing the parts in their different successive positions to illustrate the actions of the mechanism. Fig. 8 is a diagram of a modification.

Turning to the drawings, I will first refer to the diagrammatic views in Figs. 4, 5, 6, and 7, which illustrate the principle and'action of my invention in a simpler and more direct manner. In these views, a indicates the lower die or matrix, which is fixed to the bed or table of the machine in the usual way, and which contains on its face the cavity or recess adapted to the shape of the pan or vessel to be formed or drawn.

b,-Fig. 4, indicates the flat blank of sheet metal placed on the die and to be stamped or drawn into the desired form. i

0 indicates the reciprocating blanloholder, which is of annular or hollow cylindrical form, and which is adapted to descend at the proper moment upon the edge of the blank, as seen in Fig. 5, to hold it firmly upon the die while the center of the blank is being stamped o1- drawn into the hollow of the die.

d indicates the reciprocating plunger or patrix, which moves within the interior of the to descend at the right moment against the blank sheet and force it into the hollow of the die, while the blank is held forcibly at its margins by the blank-holder c, as shown in Fig. 6, thus drawing or stamping the sheet metal into the desired form. On the return or up stroke of the plunger, as seen in Fig. 7, the blank-holder still continues to hold until the plunger is retracted from the die and from the article formed therein, when blank-holder and plunger then rise together, as seen in Fig.

l hollow cylindrical b1ank-holder,and is adapted 4, permitting the removal of the stamped article and the placing of another blank in posi' tion for a repetition of the actions, as shown in Fig. 4:. It will therefore be seen that the described actions of the press require that the blank-holder have a considerable pause in its motion, so as to hold the blank firmly while the plunger is moving to force it into the die. This pausing and holding action of the holder relatively to the stroke of the plunger is effected in a simple and reliable manner by the mechanism'best shown in the diagrammatic views. In these views, f indicates a crankshaft, to which the power is applied and which makes but one revolution at a time, as usual in presses, each revolution producing one complete action of the press and forming one arti cle, as is usual in this class of machinery. Now on this crank-shaft is a main crank, e, which is directly connected by a pitman, g, or other connection with the plunger d, the pitman being of course preferably adjustable in length in the usual maner, as illustrated in Fig. 1.

As seen best in Figs. 5, 6, and 7, h indicates what I may term a reciprocating driver or cross-head, which reciprocates i n line with the plunger, and is connected indirectly with the blank-holder c by a system of toggles or links and crank-levers, by which, chiefly, the peculiar pausing and holding action of the blankholder relatively to the stroke of the plunger is effected. This reciprocating driver or crosshead is driven or reciprocated by a second crank, t, on the crankshaft f, the crank-pin of which engages a square sliding block, g, which moves in a horizontal slot or groove, 3', in the cross-head h, the cross-head being of course guided in vertical guides, so that the revolution of the crank 'i imparts a true vertical reciprocation to the crosshead, while the slotj and sliding block q allow the free horizontal swing of the crank without interfering with the vertical motion, as will be readily understood. The cranks 671 are preferably arranged at a distance apart of about onethird the circumference, but they may be set exactly opposite; but I prefer their nearer position, as will be hereinafter shown.

Now, It indicates two toggle-links,which are pivoted alongside the cross-head on fixed axes and they are preferably made with opposite and equal arms is k, as shown. The inner arms are connected by short links m m with rigid projections on the cross-head h,while the outer arms are connected by toggle-links n n with the blankholder c. The toggle-links it should be provided with an adjustment for length, or their connection with the blankholder should be adjustable, or the blankholder should itself be adjustable in length to regulate the length of the effective stroke of the blank-holder, as will be understood, such adjustment being shown in Fig. 1 in a practical way.

It may now be seen on reference to Fig. 4 that the operative connections of the plunger down the blank-holder h.

and blankholder with the crank-shaft are such that when the machine is in repose both plunger and blankholder will be at or near the top of their stroke and the cross-head It will be at the bottom of its stroke, the toggle-links k is being nearly horizontal,while the short links m are vertical and the toggle-links n inclined to the vertical. It will therefore be noted that if the crankshaft now revolves in the direction of the arrow the cross-head h will move upward, thus causing the links m m to force or swing the toggle-links k k around toward their vertical position, which will of course depress the toggle-links n n and force As the blank-holder descends, the crank 6 will also now force down the plunger (1, the two moving together; but the blank-holder will move in advance of the plunger, as seen in Fig. 5, until the blankholder reaches and bears upon the blank 1) upon the die a, when it will be pressed firmly thereon and now remain at rest, holding the blank firmly on the die while the plunger continues to descend rapidly within the stationary holder and against the blank, as seen in Fig. 5. At this instant it will be seen that the crank i will be passing through its arc of least effect at its upper dead-point, while the cross-head his in the position of a tangent or chord to this are of least effect, and hence during the swing of the crank through this are (about one-quarter of the circle) very little motion will be imparted to the crosshead. It will be further seen that what little motion is imparted at this time to the cross-head will be neutralized so far as its transmission to the blank-holder is concerned by the effect of the toggle-links a and links m, for in this position it will be seen that the links m will be at right angles to the stroke of the cross-head h, and hence their are of motion will be tangent to the stroke of the crosshead while the togglelinks k 7c will be parallel to the stroke of the cross-head, and the toggle-links n n in line with the crank-levers; hence after the blank holder reaches and bears firmly upon the blank the only motion imparted to the cross-head h by the further rotation of the crank i (see Fig. 5) will be that equal to the sine of the cranks arc to which the cross-head is the chord, as indicated by the dotted lines, and while the cross-head is moving through this sine the only motion imparted thereby to the toggle-links k it through the connecting-links in will be that representedby the sine of the arcs in which the links m swing, as shown by dotted lines,which is practically nothing, and even if very slight will be actually reduced to nothing at thejoint between the togglelink 7c and toggle-link n, which are in line and will therefore have no effect on the blank-holder except to hold it more firmly in its pausing and holding position; hence while the crank i is at its position of least effect and moves through about one-quarter of its circle at its upper deadpoint no further motion will be imparted to ICO IIO

v the blank-holder while the other crank, e, is

movingthrough its arc of greatest effecttha-t is, from the position shown in Fig.5 to the position shownin Fig. 6,orabout one-quarter of the circleso that hence as soon as the blankholder reaches and bears firmly upon the blank it remains at rest in said position, as seen in Fig. 5, while the plunger now descends rapidly, as shown in Fig. 6, and forces the middle part of the blank into the die, thus drawing or stamping the metal into the desired shape. As the rotation of the -cran ks continues, as shown in Fig. 7, it willbe seen that the plunger will rise out of the die a lit tle before the blankholder relaxes its hold on the work, thus causingthe plunger to retract itself from the work, after which blank-holder placing of another blank in position for the next action. It will therefore be seen that by this mechanism the desired relative motions of the plunger and blank-holder are produced in a very simple and efficient manner,the pausing and holding action of the blank-holder while the plunger is entering the die being produced without any cam action whatever, but solely by cranks and jointed toggle links or bars, whose joints are constantly engaged or connected, and in which there is comparatively little friction or wear, and which therefore has the great advantages of being strong and simple in construction, durable and efficient in action, and having a great range of wear without requiring repairs or adjustment, which is not the case with cam mechanism.

It will be noted that by having the cranks e i set nearer than a diametrical position the plunger-crank 6 will have a longer and more effective stroke when the other crank, z, is passing through its arc of least effect; but the cranks may of course be set directly opposite or at any other distance apart, according to the particular extent of stroke desired, as will be readily comprehended- By'now referring to Figs. 1, 2, and 3, the practical construction of a press embodying the principles illustrated in the diagrams will be readily understood. In these views Figs. 1, 2, and 3, like parts are of course lettered similarly to the corresponding parts in the,

diagrams, which parts will be found practically identical in both cases. Turning, therefore, to Figs. 1, 2, and 3, it will be seen that the die a is fixed upon the bed or table 5 of the press, from which table arise the strong side standards, 25 t, connected at the top by the arched head 15. The main crank-shaft f is mounted in hearings in the top of the standards t t, and extends centrally and transversely through the said standards. The crank i on the middle of the crank-shaft between the standards is connected by an adjustable pit man, 9, of well-known kind, as seen best in 1, with a short cross-head, g, which moves in guides g" on the interior of the hollow cylindrical cross-head 0, connected to the blankholder 0, as best seen in Fig. 2, and to this short cross-head g is connected the plunger or plete revolution on the depression of a treadle V and then stop automatically at the end of the revolutionsuch, for example, as that shown in my patent, N 0. 370,198, of September 20, 1887. This clutch device is shown partly at o in Fig. 1, 1) being the operating treadle-rod; but I have not, of course, shown any detail views of this clutch, as it forms no part of my invention and is well understood in the art.

The gear-wheel u (see also Figs. 2 and 3) is driven by a pinion, u, on the end of a driving-shaft, 10, which is mounted in bearings near the base of and at the back of the standards t, and on the opposite end of this shaft is fixed a flywheel, w, and a driving-pulley, w to which the power is applied to constantly revolve the fly-wheel and driving-shaft and the gears u a, while the crankshaft f is revolved only onceat a time to produce the stamping aetion,when the treadle-rod o is depressed according to the method usual in operating machines of this class. On the opposite end of the crank-shaft) is fixed the crank or crankdisk 2, which actuates the blankholder. The pin of this crank engages the sliding block q, as seen best in Fig. 1, which slides in the horizontal groove j in the crosshead h, which is guided vertically in the upright guide-bars h, standing out from and secured to one of the standards t, as fully shown in Figs. 1, 2. and 3. These standards have a forked or U shape at the top in the region of the crosshead h, as fully shown in Figs. 3,. 2,

IIIO

and 1, to better accommodate the moving parts.

At the top of the standards, upon each side, are journaled the rock-shafts k (see Figs. 1, 2, and 3,) from which the two arms of the toggle'links k k radiate. The arms k on the outer end of the rockshaft are connected with the top of the cross-head h by the links m,- while the arms k on the middle or inner part of the rock-shaft are connected by the toggle'links 71,, preferably four in number, with four adjustable screws, a, secured to a hollow cylindrical cross-head, c, to which the blank-holder or blank-holding die a is secured, as fully shown in Figs. 1 and 2. The cylindrical crosshead 0 is guided in guides don the inner faces of the standards t, as best seen in Fig. 1.

The elements shown in Figs. 1, 2, and 3 are of course identical in arrangement and action with those shown diagrammatically in Figs. 4, 5, 6, and 7, and hence nofurther description of the operation or action of Figs. 1, 2, and 3 is necessary, as it is identical with that already given in referringto the diagrams.

It may be seen on reference to Fig. 5 that the parts m k may be regarded as one set of toggles 'or knee-joints, and the parts 11. 7c another set of toggles, and that the toggles m, 70' are bent at right angles when the blank-holder is in its holding position and the crank imoving through its are of least effect, while the toggles 70 n are in line at the same time. It will be further seen that the two pairs of toggles are duplicated on opposite sides of the center of the dies, in order to produce a balanced mechanical arrangement; but the principle of my invention is of course embodied in one set of the toggles, and the duplication may be more or less, according to mechanical convenience without altering the principle of my machine, so thatI do not, of course, confine myself to any particular number of the sets of toggles beyond the least practical number indicated.

In Fig. 8, where the system of toggles is placed at the bottom of the press, only singlearmed toggle-links k are used, and both link m and toggle-link n arejointed to the ends of said togglelinks. In this modification the crankshaft f is at the top of the press, as usual, and the cranks e i are set in an equiva lent position to that already described, as will be understood from the diagram in Fig. 8. The togglelinks 7c are pivoted on the base or table of the press-frame at each side, and two sliding cross-heads h are usedone on each side-guided in vertical guides on the side frames, t, adjacent to the toggle-links it, each of these cross-heads h being connected by a pitman, Z, to the cranks or eccentrics i i on the ends of the crankshaft f. The cross-heads h are operatively connected to act in unison by a strong crossconnecting tie-rod, h, the ends of which project to engage the pitmen Z. The cross-heads h are connected by the links mdirectly to the toggle-link k, as before; but the togglelinks it also connect directly to the toggle-link 70, while the opposite ends thereof connect to a rigid cross-bar, 0 which is guided in a true vertical position and connected to the blank-holder c. The action is substantially the same as that described in referring to the other figures, and is identically the same in principle and result.

In Fig. 8 the dotted lines show the position of parts when the blank-holder and plunger are at the top of their strokes or corresponding to Fig. 4, while the full lines show the parts in the holding and stamping position corresponding to Fig. 5. It will therefore be seen on referring to the full lines in Fig. 8 that when the blank-holder reaches the die the cranksz' will be at their lower dead-points or passing through their are of least effect, the togglelinks 70 will be parallel with the cross-heads h, and the links 111. at right angles to both, and therefore in the tangent position of no effect, while the toggle-links n are in line with the toggle-links 7c in the position of no effect, so that the action and result will be precisely the same as that shown in the main figures.

WhatItherefore claim as my invention is- 1. In a press of substantially the described kind, the combination, with a fixed die, a reciprocating plunger, and a reciprocating and pausing blank-holder, of a toggle-link, k, a link connected to the toggle-link, a drivingcrank connected by a reciprocating bar to the link, and a second togglelink connected to first toggle-link and to the blank-holder, ar

ranged and operating substantially as and for the purpose herein shown and described.

2. In a stamping or drawing press, the combination, with a fixed die and a reciprocating plunger and a reciprocating and pausing blankholder, of a toggle-link, k, a toggle-link, n, connecting said blank-holder with said toggle link is, a reciprocating driver or crosshead, h, a link, m, connecting said cross'head to said toggle-link k, and two driving-cranks, e i, set in opposite or nearly opposite positions, and one connected to said plunger and the other to said cross-head, arranged and operat' ing substantially as and for the purpose herein set forth.

3. In a press, the combination, with the fixed die a, reciprocating plunger d, and reciprocating and pausing blank-holder c, of a centrallyarranged driving crank shaft, f, and two cranks, e i, pitman 9, connecting crank e and plunger d, cross-head h, connected to crank 2', with the toggle-link 7c, toggle-link n, connecting said toggle-link k to the blank-holder, and link m, connecting the toggle -link It to the cross-head, substantially as herein shown and described.

FRANK M. LEAVITT.

Witnesses:

J NO. E. GAVIN, CHAS. M. HIGGINS. 

